1. Field of the Invention
This invention relates to slide fasteners and more particularly a slider therefore which is switchable between locked and unlocked positions.
2. Prior Art
There are known various types of the so-called lockable sliders, a typical example of which is a slider having a key lock mechanism as disclosed for instance in Japanese Utility Model Publication No. 62-32415 and another example is a slider having a stopper means operatively associated with a slider pull tab as disclosed for instance in Japanese Utility Model Publication No. 56-37607. Most key-lock sliders are designed with the use of a key to keep the slider in locked position in which a locking prong extends into a guide channel for the passage of coupling element rows on slide fastener stringers and release the slider into unlocked position in which the locking prong is freely movable into and out of the guide channel, or alternatively switch the key to hold the locking prong retracted away from the guide channel. Sliders of the other type are constructed such that a stopper means often in the form of a locking prong integral with the pull tab is retracted from the guide channel by pulling the pull tab in one or the other direction and brought into engagement in between the coupling elements by flipping the pull tab flat against the slider body to prevent unintentional movement of the slider along the slide fastener. Since the latter type of lockable slider is easily released from its locked position by manipulating the pull tab, the user would often unconsciously leave his garment or bag with the slider unlocked thereon, posing a theft or other security problem. Whereas, the key locking type of slider literally requires the user to carry with him a key in which instance such key is liable to get lost. It would also be embarrassing to put a key on a person. Furthermore, keys are by nature tedious to handle and hence would often be left unused.